[omgwtfbbq]

>a 25 year-old developer is the same as a 50 year-old developer, but at half the cost and without the hassles of things like kids to take care of

Bunt functionally this is correct. If they are both "Senior Devs" they're going to be roughly equivalent. If you are 50 and haven't gotten architect/tech-lead/principal roles etc. you're probably at your ceiling and you aren't really going to be much more valuable than that 25 year old.